Armageddon -- 2419 A. D.

Nowlan’s novella tells about the United States in the 25th century, conquered by Hans in 2109 AD and only now beginning to rebel. Sometime after World War I, nearly all the European powers joined forces against the United States. Although the US won the war, both sides were devastated by the conflict. Taking advantage of the chaos that followed, the "Russian Soviets" (Soviet Union) joined forces with the "Mongolians" to take over Europe. The US collapsed economically and stagnated while the "Mongolians" turned against the Russians and defeated them as part of their campaign of world conquest.

American efforts to avoid war with the "Mongolians" failed, and in 2109 AD, the latter attacked the US using fleets of airships armed with disintegrator rays. They attacked from the Atlantic and Pacific coasts, and down from Canada. After conquering the US and Canada, these "Airlords of Han" ruled North America as a province of the world empire, from 15 great cities they established across the continent. They ignored the Americans, who were left to fend for themselves in the forests and mountains as the "Mongolians'" advanced technology prevented the need for slave labor.  From time to time, they raid American land "to keep the 'wild' Americans on the run within the shelter of their forests, and prevent their becoming a menace to the Han civilization."

Living in cooperative gangs and hiding in the forests from the Hans, Americans secretly rebuild their civilization and develop the new technologies "inertron" and "ultron". Inertron is a substance with "reverse weight" (anti-gravitational properties), so that a person carrying an amount of inertron equal to most of his weight (in the form of a “jumper” – "rocket motors encased in inertron blocks and strapped to the back") can travel rapidly across country in long leaps. Ultron, in turn, is an "absolutely invisible and non-reflective solid of great molecular density and moderate elasticity, which has the property of being 100 percent conductive to those pulsations known as light, electricity and heat." The Americans use these technologies, as well as explosive rockets and radio frequencies the enemy cannot detect, in their struggle with the Hans.